title: The intracellular expression pattern of the human papillomavirus type 11 E1--E4 protein correlates with its ability to self associate.
abstract: The function of the human papillomavirus type 11 (HPV 11) E1--E4 spliced protein is not known. E1--E4 protein in HPV-infected tissue is detected in the cytoplasm of differentiated epithelial cells and as immunoreactive bands corresponding to potential monomers, dimers and trimers in immunoblots. The yeast two-hybrid system was employed to test for self association of the HPV 11 E1--E4 protein. To confirm the results of the yeast two-hybrid experiments, coimmunofluorescence studies of a green fluorescent fusion protein (GFP-E1--E4) and a T7 epitope-tagged E1--E4 protein were performed in C33a keratinocytes. E1--E4 protein was shown to self associate in the yeast two-hybrid system, and this result was confirmed by colocalization of GFP-E1--E4 and T7-E1(wedge)E4 proteins in keratinocytes. Analysis of E1--E4 mutants established that the C-terminus was required for self association and that sequences in the N-terminus influenced the intracellular localization of E1--E4 protein. The intracellular expression patterns of GFP-E1--E4 and GFP-E1--E4 mutants were correlated with E1--E4 binding in the yeast two-hybrid system. Those E1--E4 mutants that did not self associate in the yeast two-hybrid system were detected as diffuse cellular fluorescence when expressed as GFP fusions. In contrast, GFP-E1--E4 was detected as a perinuclear aggregate. All E1--E4 mutants capable of associating with E1--E4 in the yeast two-hybrid system were detected as aggregates when expressed as GFP fusion proteins in keratinocytes.
authors.affiliation: Department of Microbiology and Immunology, Divsion of Infectious Diseases, Indianapolis, Indiana, 46202, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Bryan
authors.forename: K H
authors.initials: KH
authors.lastname: Fife
authors.forename: D R
authors.initials: DR
authors.lastname: Brown
mesh_terms: D000818:Animals; D019556:COS Cells; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D007424:Intracellular Fluid; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism*; D027383:Papillomaviridae / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012441:Saccharomyces cerevisiae; D014407:Tumor Cells, Cultured; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C084304:E1 protein, Human papillomavirus type 11; D009856:Oncogene Proteins, Viral; D014764:Viral Proteins; C067860:oncogene protein E4, type 11, Human papillomavirus